The present invention relates in general to electrical switches, and more particularly to a novel and improved pressure-actuated switch suitable for use in relatively high pressure applications, such as in a hydraulic power steering system.
It is known in the art to use a snap-disc-actuated switch for monitoring fluid pressures. U.S. Pat. Nos. 3,335,242; 4,121,073; 4,121,074; and 4,145,588 all disclose a switch for such use wherein the pressurized fluid impinges directly on the snap disc over the extent of its fluid-exposed surface area.
Optimum operating and structural characteristics of a conventional snap disc of the type under consideration require that the disc snap from its stable state position of first curvature to its opposite position of curvature, which is the switch-actuating state, at a relatively low applied force, e.g., 10 lbs. To monitor a relatively high fluid pressure, e.g., 550 psi, in accordance with the teaching of the noted patents, supra, it would be necessary to provide a very stiff disc having a very high operating force. Because it is impractical to accurately provide such a stiff disc, disc devices of these patents have been limited in their use to the monitoring of relatively low pressures.
In one aspect, the present invention provides a snap-disc-actuated switch for monitoring high fluid pressures, such a switch utilizing a low-force-actuated snap disc of conventional design.
In a further aspect, the present invention provides a high-pressure-actuated snap disc switch that is reliable, simple in construction, and low in manufacturing cost.